Manufacture of dried granular solids



July 22, 1941. A. a. JONES MANUFACTURE OF DRIED! GRANULAR SOLIDS Filed July 9, 1938 flJmM/ZVENTOR.

ATTORNEYS Patented July 22, 1941 2,249,960 MANUFACTURE or pump Grumman soups Arthur B. Jones, New York, N. Y., asslgnor to Industrial Associates, Inc., New York, N. Y., a

corporation of New York p I Application July 9, 1938, Serial No. 218,349 1 Claim (Cl. 252-367) Q This invention relates to the manufacture of dried granular solids, especially soap, from mixtures thereof with liquids, the resulting dried granular solids varying in such physical characteristics as bulk density, size, shape and moisture content.

In the manufacture of soap, at the completion of the formation of the soap, it exists in a kettle in molten state containing varying percentages of water. However, if the soap production is so conducted that the'molten kettle soap is caused to contain the highest percentage of solids consistent with proper progress of the saponiflcation reaction and with the requirement that the kettle soap must be suitable for handling, granules or powder produced by the spray or other flash drying of the kettle soap will have an undesirably low bulk density. For example, the flash drying of molten kettle soap having in the neighborhood of 40% or more of solids produces a powder having an apparent density (specific gravity'of the mass of particles) of .22 or less; and so conductingthe soap-forming operation as to increase the concentration of the molten soap up to even 60% of solids, at the risk of impairing the chemical reaction and also obtaining a kettle soap that cannot be handled, does not give by flash drying an apparent density exceeding .26. numerous objections to soap powder of such density, including excessive packaging cost due to the light bulk weight of the soap powder.

The nature of soap, especially its dissol ing or dispersing characteristics and its forming and emulsifying tendencies, make it impossible or economically prohibitive to mix soap as ordinarily produced with kettle soap to produce a mixture of such properties and concentration that powder or granules of desirable apparent density can be produced therefrom by asingle flash drying. In accordance with this invention mixtures of soap and water, or molten soap, which can be handled The-re are but .which nevertheless have such high concentration of soap that the flash drying thereof in a single flash-drying operation produces powder orv granules having an apparent density of .31 to .35

' or higher, are produced by adding to and mixing with the molten kettle soap of limited concentration, granular or powdered soap obtained by flash drying of the mixture. Thus, in accordance with this invention, while it is impossible to produce in the manufacture of soap a molten kettle soap, or a mixture thereof with soap ordinarily produced, having sufficiently high concentration of solids to give a powdered or granular product of sufficiently high apparent density by flash drying,

' erties, be combined with the molten kettle soap to give a mixture having such concentration that the granular .or powdered'product obtained. by a single flash drying of the mixture has the acceptable higher apparent density.

In the practice of this invention, the production of granular or powdered soap having an apparent density of .31 to .35 or higher may be continuous. In continuous procedure, in accordance with this invention, the molten kettle soap resulting from soap manufacture is fed to a single spray-drying operation and the first dried product produced is of undesirably low apparent density and it is all or in part fed back to and mixed with the molten kettle soap passing to the drying operation, thereby increasing the concentration of solids in the material actually spraydried and causing the apparent density of the spray-dried mixture to rise to a desirable apparent density, e. g., .31 to .35 or higher. Thereafter, the dried product being passed to and mixed with the molten kettle soap is no longer a product of objectionably low apparent density but is a product of acceptably higher apparent density and may be of commercially acceptable particle size, and in accordance with this invention such a dried product continues to be added to and mixed with the molten kettle soap passing to the drying operation but only a limited part of the order of approximately 10% to 40% of the dried product is so returned to the molten soap having a desirably high apparent density.

In the spray-drying of the soap the main portion of the dried product is collected in the bottom of the drying chamber, but a portion is carried from that chamber by the drying gases passed therethrough and is removed from the catcher.

emerging gases by a cyclone or other type of dust The dried product carried out by the gases is of smaller average particle size than the product failing to the bottom of the drying chamher, but it is of relatively high apparent density.

The dried product of high apparent density added to the molten kettle soap to increase the solid content thereof in the practice of this invention may consist of the material collected in the dust catcher, or may consist of the material of higher average particle size which collects on the floor of the drying chamber, or may consist of a mixture of these two materials.

In the practice of this invention, the observance of certain precautions will facilitate the attainment of the maximum benefits thereof. It is advantageous, and usually necessary, to heat the mixture of kettle soap and dried powder recycled thereto. The mixing of the recycled powder with the kettle soap should continue for a long enough period to facilitate the elimination of air from the resulting mixture. The mixer should be so constructed and operated as to avoid introduction of air into the mixture of kettle soap and powder, and the formation of soap emulsions, which would be promoted by such introduction of air, should be avoided b'ecause emulsification of the soap defeats the object of the mixing operation and the production of powder of high apparent density.

Efforts have been made heretofore to solve the problem which has been effectively and economically solved by this invention, namely, the production of dried soap powder having relatively high apparent density from molten kettle soap which cannot be produced in the manufacture of soap with sufficiently high solid concentration to give by flash drying a soap powder of acceptable apparent density and cannot be mixed with ordinary soap to achieve that end. Thus, it has been proposed to flash dry the molten kettle soap to produce a dried powder of undesirably low density and then to mix that powder with molten soap and then subject the mixture to drying in a successive and separate drying operation. Also, it has been proposed to subject the kettle soap to a preliminary concentration in one drying op. eration and then subject the concentration to a successive and separate drying operation. In the latter proposal, dust was returned to the concentrating operation, but even so, two successive and separate drying operations and the apparatus necessary therefor were indispensable.

In accordance with this invention, it has been discovered that dried powder of commercially acceptable density can be mixed, especially under the particular conditions of this invention, with unconcentrated kettle soap to produce a mixture, without other concentrating treatment, having such concentration of solids and such physical form that there may be produced therefrom by a single flash-drying operation, a dried product having acceptably high apparent density.

Further to disclose this invention there is shown in the single figure of the drawing apparatus suitable for the practice of the invention and the practice of the invention is described in connection therewith, with the understanding that the invention is not limited to the apparatus disclosed or to the specific features of operation described.

The drawing shows diagrammatically in elevation apparatus whereby the invention may be practiced. The raw solution or molten material or slurry is fed to a mixer I as by a pipe 30 wherein mixing without emulsiflcation or introduction of air is effected as by a motor-driven impeller 3|, or in any other suitable manner. While the material from mixer I can be spray-dried in any suitable manner, a centrifugal or other mechanical atomizer is preferred. and is indicated diagrammatically in the drawing. The mixture leaves the mixer I through pipe 2 and is passed by pump 3 through pipe 4 to the atomizer 5 which may be constructed in accordance with U. S.

Patents Nos. 1,732, 1 1.759.62 1. 1,779,336, etc. to Riley and Spross. The revolving bowl 6 of the atomizer disperses the mixture within the drying chamber I to which is fed hot air, containing products of combustion if desired, produced by heater I2 and passed through pipe ii. The hot gases enter chamber Hi and pass downwardly around atomizer 5 through the openings in the partition forming the lower wail of chamber Hi. In the production of the dried product it may be desirable to chill instead of heat the molten soap and in that case the heated gases are shut oif by closing damper 20 and cold air is admitted through pipe 22 provided with damper 2! which is opened for a chilling operation and closed when heated gas is utilized. Ordinarily chilling will not be employed because it removes but a low percentage of water. The fine particlesinto which the mixture is dispersed by reason of the high speed of the revolving bowl 6 are dried by the gases passing into chamber 1 and passing therefrom through pipe l4. Pipe It leads to a cyclore 'or other type of dust catcher |5 from the bottom of which dust passes through pipe 23 and from the top of which the gases pass through pipe it under the action of a suction fan I] driven by motor l8, the gases being discharged to the atomsphere through duct IS.

The dried powder falls to the bottom of chamber 1 and is collected by rake 8, driven by shaft I 3, and removed through spout 9. If the bottom of chamber I is cone-shaped with sufficient pitch to discharge the dry powder, rake 8 may be omitted.

The dried powder from the bottom of drying chamber 1 passes through spout 9 to an apportioning device 33 which may be of any suitable construction but which is shown diagrammatically in the drawing to include a deflector plate 34 which may be adjusted to vary the proportion of powder passing through duct 35 to storage and passing through pipe 28 into boot 25 of conveyor 24.. A similar proportioning device is arranged for deflecting more or less of the powder from duct 23 into boot H. The conveyor 24 discharges solid material into mixer i which is provided.

witlhfiny suitable heating means, such as a steam co In starting the operation the first dried material is produced from raw kettle soap and is of undesirably low density and it is all returned to the mixer l until the solid concentration of the material atomized in chamber I is suflicient, approximately 65% to to give a dried product of desirable density and thereupon adjustment of the deflector plates 34 diverts to storage finished material of acceptable apparent or mass density.

I claim:

The method of producing granular soap which comprises downwardly directing a stream of hot gases, forming a fluid mixture of kettle soap and granular soap, centrifugally praying said mixture into the upper end of said stream and thereby producing granular soapby spray drying, utilizing the spray dried product as the granular soap ingredient of said mixture in proper ratio that the mixture has such content of soap as will yield by flash drying a granular soap having a mass density not less than .3 and limiting the ingredients of said mixture to kettle soap and the granular soap produced by spray drying said mixture.

. ARTHUR B. JONES. 

